Transcranial magnetic stimulation (TMS) provides a non-invasive procedure for generating magnetic fields to induce stimulating electric current to desired areas of the human body, typically targeted areas of the brain. Repetitive transcranial magnetic stimulation (rTMS) has been shown useful in treatment of a variety of neurological and psychiatric disorders (Burt et al., 2002; Fregni and Pascual-Leone, 2007; Hallett, 2007). Applying rTMS at different frequencies may allow enhancing, suppressing, or interfering with underlying neuronal activity. Further, the effects of TMS can propagate beyond the site of stimulation, impacting a distributed network of brain regions (Ferreri et al., 2010; Lisanby and Belmaker, 2000; Ruff et al., 2009; Siebner et al., 2009; Valero-Cabre et al., 2007; Valero-Cabre et al., 2005).
The rTMS technique has been used as a non-invasive treatment for a variety of medical conditions. Applications for rTMS include, but are not limited to, psychiatric disorders, such as depression, hallucinations, obsessions, and drug craving, and different neurologic diseases.
It has been recognized that many manifestations of neurological and psychiatric diseases are not solely a result of an abnormality in one isolated region of the brain, but represent alterations in brain networks and connectivity. Accordingly, interactions and connections between regions of the brain are becoming a focus of neurological research.
The subgenual cingulate region has been shown to decrease its activity in response to multiple treatment modalities and has been used as a target of deep brain stimulation (Mayberg et al., 2000; Drevets et al., 2008; Mayberg et al., 2005). Another region that has been used clinically for the treatment of depression is the left dorsolateral prefrontal cortex (DLPFC) (Mayberg, 2007; Drevets et al., 2008).